446 J. F. Whiteaves—Age of Mesozoic Rocks 
Cumshewa Inlets hold also at least four or five new species 0 
Ammonites which have recently been described from unusually 
perfect and well preserved specimens, and which seem to belong 
to genera, to sections of genera, or to species, which in Europe 
would be regarded as exclusively Jurassic in their character. 
Moreover it is now quite clear that the fauna of the Iitas- 
youco River and Sigutlat Lake rocks, which the writer at first 
regarded as of Jurassic age, is essentially the same as that of 
the Lower shales of Skidegate and Cumshewa inlets. In the 
coal-bearing strata of the Queen Charlotte Islands and in the 
voleanic rocks of the Coast Range of British Columbia, assocl- 
ated with characteristic Cretaceous invertebrates, about a dozen 
species of fossil mollusca have been collected, which the pres 
ent writer, after long and careful study, has been unable to 
separate specifically from fossils which Meek and Dr. hite 
ave described as Jurassic. A similar apparent mixture of 
“Jurassic” and Cretaceous fossils occurs in rocks immediately 
overlying the Alpine Trias, on the Peace River. ‘ 
Judging exclusively by the invertebrate fossils which pe 
contain and by the stratigraphical position which they are 54 
to occupy, the writer, in a recently published report,* has pete 
at some length his reasons for thinking that the Jurassic age 0 
certain strata in Dakota, Montana, etc., is not yet conclusively 
proved. The evidence afforded by the vertebrates of these T0° : 
is quite another question and one which hasto be considered on 
its own merits. This aspect of the case has not been discuss 
at all in the report referred to, for the simple reason that ie 
is not a vestige of a vertebrate, not even a fish scale, 1n the col 
lection reported on. Sead 
n a paper “On the Jurassic Strata of North America, Pil" 
lished in the March number of this Journal, Dr. C. A. hite 
objects to the present writer’s suggestion that some of the anf 
Jurassic rocks of the Western States may possibly be 1 
iddle Cretaceous agé, and to the identification of a few foss! 
mollusca upon which this suggestion was based. ; 
_ Dr. White’s long experience as a paleontologist and his pe 
tensive knowledge of the fossil invertebrates of the Unitee 
: its 
* Mesozoic Fossils, vol. i, Part 3; On the Fossils of the Coal-Be aes 
rear . M. Dawson in 1878. 
of the Queen Charlotte Isla: 
teal. 21684, ds, collected by Dr. G 
